Scouse Day is an annual festival in Liverpool.
Wikipedia gives a complex list of dubious origins for the word. The one clear fact is that it was originally Lobscouse.
My favorite British dictionary from 1867 says:
Lobscouse, a dish made of potatoes and meat and biscuits boiled together.
The dictionary doesn’t list scouse at all.

Lob is the obvious part, basically a lump and by extension a stew or soup with meat, as in the more familiar loblolly. Allegedly lobscouse came from Lob’s Course meaning Lob’s meal or dish, but that doesn’t seem likely to me. Another source claims descent from Latvian labs kausa, a good dish or plate. I’d be inclined toward Dutch kaas meaning cheese, which seems to be part of related foods like headcheese. My favored dictionary lists cassam as another variant of cheese.
Even more peculiar, some references to this day misspell scouse as science, a blatant typo. No possible connection. Everyone knows that science is “the practice of torturing all human beings and obliterating the universe to settle a meaningless bet between two insane academicians.”
